"The 'mad Australians' was a common description. Not so mad - brave, heroic, turning the tide of history, making history."

A century ago the sun was low over the Negev desert as Australian horsemen nervously lined up to charge into history.

These days a Bedouin camp sits in the hills where they lined up, five kilometres from the city of Be'er Sheva. Power lines, irrigated fields and a railway track carve the plain that they crossed, first at a trot, finally at a gallop.

And the high-rises of the modern city shade the old wells that were the Anzacs' military target.

The capture of Beersheba was part of a bigger plan to trap and destroy the main Ottoman forces in Palestine, but it had been moving slowly.

Beersheba broke the back of the Ottoman resistance - though a fierce rearguard action by the Ottomans lasted another year - and it set the stage for the creation of the modern state of Israel.

On the same day, October 31, 1917, the British War Cabinet approved the text for the Balfour Declaration, which announced British sympathy for Zionist aspirations, a pivotal part of the chain of events leading to the Israeli declaration of independence in 1948.

On Tuesday political leaders from Israel and Australia, Anzac soldiers' descendants and others wishing to honour their memory gathered in Be'er Sheva to remember.

Mr Turnbull said the troops' horses were as legendary as the men that rode them. He told a story about an "unrideable rogue" horse called "Bill the Bastard" - a joke that wasn't lost on opposition leader Bill Shorten who was also attending the ceremony (though it may also have been a backhanded compliment - Bill the horse was said to have power, intelligence and unmatched courage, and was called Australia's greatest warhorse).

Israeli Prime Minister Benjamin Netanyahu said the "great dash" of the Australian Light Horse had "liberated Beersheba for the sons and daughters of Abraham, and opened the gateway for the Jewish people to re-enter the stage of history.

"The heroism of your fallen men will never be forgotten," he said.

In a speech that often took a political edge, Mr Netanyahu compared the courage of the Anzacs to the modern Israeli army.

When he joined the Israeli special forces 50 years ago he was given an Australian hat, he said, and sat under Australian eucalyptus to hear the stories of the Anzacs.

"We drank it in, it stood as a shining example for us," Mr Netanyahu said.

"The few won against the many. That's the spirit of the army of Israel??? we seek peace with all our neighbours but we will not tolerate any attacks on our sovereignty, on our people, on our land, whether from the air, the sea, the ground or below the ground."

The latter was a reference to the Israeli army blowing up a Hamas tunnel on Monday. The tunnel ran from the Gaza Strip into Israeli territory, and reportedly at least seven people were killed and another 12 injured. The Gaza Health Ministry said it was the deadliest incident in Gaza since the 2014 war.

Mr Netanyahu said he believed the Anzacs who fell at Beersheba would be proud of the deep and enduring alliance between Australia and Israel, who "stand on the same side of history, the right side of history".

Modern attention rests on the charge itself, one of the few successful cavalry charges in the 20th century.

But on Tuesday, the chief of the New Zealand Army, Major-General Peter Kelly, reminded the gathering of the vital and hard-fought role that his country's troops played on the day.

The New Zealand Mounted Rifles Brigade, supported by Australian and British units, took Tel el Saba, a well-entrenched Ottoman garrison on a hill that dominated the plain to the town's south and east.

"(The garrison) included a machine-gun company whose weapons could sweep the approaches to Beersheba," he said.

"The New Zealanders??? launched their assault up (the hill's) steep rocky slopes. After much hard fighting they secured Tel el Saba. With the hill in New Zealand hands, the door was open for the light horsemen of the Australian Mounted Division to launch their famous charge into Beersheba that completed the rout of the enemy forces and secured the town and its vital wells.

"Beersheba is but one example of the Anzac brotherhood in arms, of the kind that has been seen on so many other battlefields since."